Various disinfectant compositions have hitherto been used for disinfection of the site of operation, wounded sites, burnt skin, and infected skin.
Disinfectants containing iodine as an active ingredient exhibit bactericidal activity on various bacteria. Such iodine-based disinfectants typically include iodine tincture and povidone-iodine solution.
Since iodine is sparingly soluble in water, iodine tincture is prepared by adding to iodine potassium iodide and ethanol to dissolve. This preparation strongly irritates the skin. If iodine tincture is diluted with water in order to allay the skin irritation, part of iodine is precipitated to lessen the bactericidal activity.
Povidone-iodine solution is an aqueous solution of a polyvinyl pyrrolidone-iodine complex. Disadvantages of povidone-iodine solution lie in its relative expensiveness and strong complex-forming ability of polyvinyl pyrrolidone which sometimes requires concentration adjustment for manifestation of sufficient bactericidal effects.
Disinfectants are required to exert potent bactericidal activity on a broad range of bacteria and to have skin irritation minimized. It is desirable that disinfectants also have viricidal activity in addition to these requirements.
While it has been reported that the bactericidal and viricidal activities essentially exhibited by iodine-based disinfectants are attributed to free iodine of unbound form, a higher free iodine concentration is known to induce stronger irritation to the skin. It is important, as is implied by this fact, to preliminarily grasp a proper range of free iodine concentration in which bactericidal and viricidal activities can be manifested while suppressing skin irritation and to establish a method for easily and appropriately setting the free iodine concentration within such a proper range.
It is also important for an iodine-based disinfectant composition to contain an adequate amount of iodine in a bound form, e.g., a complex form, so as to make up for the loss of free iodine resulting from consumption during disinfection. Further, the amount each of free iodine and bound iodine and the free iodine to bound iodine ratio should be determined taking the end use of the disinfectant composition into consideration. Thus, it is also of importance that these factors may be arbitrarily adjusted.